Control system



March 25, 1952 G. P. LESSMANN 2,590,628

CONTROL SYSTEM Filed Aug. 10, 1945 3 Sheets-Sheet l Confr'o/ Y Gonfra/ INVENTOR 6rhard 16.5fm m,

' WITNESSES:

March 25, 1952 p, LESSMANN 2,590,628

CONTROL SYSTEM Filed Aug. 10, 1945 3 Sheets-Sheet 2 WITNESSES: INVENTOR GerhardP/essmann. Q2). a Z: @5 g g/W ATTOR EY March 25, 1952 G. P. LESSMANN 2,590,623

CONTROL SYSTEM Filed Aug. 10, 1945 3 sheat s-Sheet s INVENTOR erbaro plei-fmana WITNESSES:

Patented Mar. 25, 1952 CGNTRGL SYSTEM Gerhard P. Lessmann, Pittsburgh, Pa., assignor to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application August 10, 194.5, Serial No. 610,123

(Cl. 8il-35) 11 Claims.

My invention relates, generally, to tension control systems, and it has reference, in particular, to tensioning devices and tension indicating devices for respectively subjecting a strip of material to tension, and indicating the degree of tension therein as the strip passes between adjacent work devices.

Generally stated, it is an object of my invention to provide a double-range tensiometer which is simple and inexpensive to manufacture, and is easy to operate.

More specifically, it is an object of my invention to provide for operating a single tensiometer for producing or indicating relatively high and relatively low values of tension.

Another object of my invention is to provide for increasing the operating range of tensiometers to provide for operation at high as well as low values of tension.

Yet another object of my invention is to provide a double-roll tensiometer wherein a strip of material may be operatively positioned for producing either high or low values of tension without having to thread the strip back and forth around the rolls.

Still another object of my invention is to provide a tensioineter which may be changed from a relatively high to a relatively low operating range of tension values without changing the inertia characteristics thereof.

It is also an object of my invention to provide for movably positioning the rolls of a double-roll tensioineter relative to each other in order to permit threading a strip in substantially a straight line between the rolls, and then, moving the rolls relative to one another to produce a double deflection of the strip.

An important object or" my invention is to provide for movably positioning a pair of tension rolls in a double roll tensiometer for so operating in different positions with either one or both of the rolls engaging a strip of material that in each case the roll or rolls are maintained at an angle of from 30 to 60 degrees with the free path of the strip to be tensioned.

it is also another object of my invention to provide a double-roll tensiozneter wherein the roll support may be rotated in one direction about an axis intermediate the axes of the rolls to permit straight threading of a strip between the rolls and then further rotated in the same direction to the operating position.

Other objects will in part be obvious, and will in part be explained, hereinafter.

In practicing my invention in one of its forms.

a strip of material is subjected to a transverse force between adjacent roll stands by a tensiometer having a pair of spaced apart rolls rotatably mounted on a support which is itself rotatable about an axis parallel to and intermediate of the axes of the rolls. The support is detachably connected to fluid pressure or other suitable actuating means for biasing the rolls against the strip to produce a predetermined tension therein. Regulating means responsive to the operating position of the rolls control the relative speed of the roll stands to maintain a predetermined tension in the strip. When the tensiometer is operated in the high-tension range, the strip passes over the upper roll in the usual manner. When it is operated in the low-tension range, the strip is first threaded between the rolls which are then rotated about a common axis so that the strip is doubly deflected by the rolls to maintain a Z or S- shaped loop and produce a lower tension therein for the same adjustment of the actuating and regulating means.

For a more complete understanding of the nature and scope of my invention, reference may be made to the following detailed description, which may be studied in connection With the accompanying drawings, in which:

Figure 1 is a diagrammatic View of a tension control system embodying the invention in one of its forms;

Figs. 2 and 3 are schematic views of the doubleroll tensiometer showing one way of threading the strip for operating in the low-tension range;

Fig. i is a schematic View of the double-roll tensiometer showing another arrangement of the strip;

Fig. 5 is an enlarged partial side elevational view of a tensiometer such as is shown schematically in Fig. 1;

Fig. 6 is a sectional View taken along the line VIVI of Fig. 5;

Fig. 7 is a sectional view taken along the line VII.-VII of Fig. 5;

Fig. 8 is a partial diagrammatic view of a double-roll tensicmeter showing an alternate form of connection between the support and pressure actuating means;

Fig. 9 is an enlarged end elevational View, partially in section, of a double-roll tensiometer illustrating a diiierent embodiment of the invention;

Fig. 10 is an enlarged end elevational view of a double-roll tensioineter illustrating yet another embodiment of the invention; and

Fig. 11 is an enlarged partial front elevational view of the double-roll tensiometer of Fig. arranged for operation as a tension indicator.

Referring to Fig. l, the reference numeral l0 may denote, generally, a tension control system wherein a tensiometer H is disposed to provide for deflecting a strip of material l2 as it passes in a direction from left to right between work devices such as the roll stands l4 and IE, to produce a predetermined tension therein.

The roll stand may be provided with a driving motor I! having an armature l8 and series field winding it connected to a source of directcurrent power represented by the conductors 20, through suitable control means 22. The shunt field winding 23 of the motor may be connected through a rhcostat 24 to a source of direct-current power represented by the conductors 26.

The roll stand I4 may be provided with a driving motor 28 having an armature 29 and series field winding 30 connected to the conductors through suitable control means 32. In order to vary the relative speed of the roll stands, the shunt field winding 33 of the motor 28 may be energized from a source of variable voltage, such as the generator 34, which may be provided with an armature 35 connected to the shunt field winding 33 and a field winding 36. The field winding 36 may be energized from the conductors 26 through a control resistor 31 and a suitable regulator 38. The regulator may comprise, for example, a tapped resistor 39, which may be shunted by a number of spring contact fingers Sta, disposed to be actuated by a lever 29 upon the rotation of a cam ll on a shaft extension 42.

In many applications different operating values of tension are necessary, which require a range of values greater than can be satisfactorily accommodated by varying the fluid pressure or spring force of the usual type of single roll tensiometer. In one application, for example, tensions of to 300 pounds were desired for the rolling of thin strip or foil, and tensions of 450 to 4500 pounds were also desired for rolling heavier strip in thesame mill.

In order to provide for tensioning the strip I2, over such a wide range, the tensiometer H may comprise a pair of tension rolls 43 and 44 movably mounted relative to each other, being either mounted in guides in a fixed support, or being, as shown, positioned on a support plate 45 which may be rotatably mounted by means of a shaft 46 about an axis substantially parallel to and transversely of the strip l2. Actuating means such as shown comprising a fluid pressure device 41 and a pressure regulator 68 may be provided for applying a substantially constant torque to the support plate 5 for biasing the roll 43 against the strip l2.

In order to maintain the tension in the strip l 2 substantially constant, suitable means may be provided for controlling the regulator 38 in response to movement of the support plate 45 and strip engaging roll 43, For example, a synchrotie system comprising a transmitter 59 and a receiver 52 may be provided for operatively connecting the tensiometer shaft 16 to the shaft extension 42, which effects operation of the spring contacts 38a, of the regulator 38 to vary the speed of the motor 28 by cutting in or out more of the control resistor 39 to speed up or slow down the driving motor 28 whenever the tension in the strip l2 increases above or decreases below the predetermined value.

When it is desired to operate in the high tension range the strip passes over the upper roll M on the sleeve 6?.

where R is the radial distance between the axis of the roll engaging the strip and the shaft 45. With the angles a and ,6 ranging from 2 to '7 degrees, and 0 in the neighborhood of 35 to 60 degrees, which are values commonly encountered in practice, this means that ZlilsgZTR cos (0 When operating in the low tension range the strip may be threaded about the rolls as shown in Figs. 3 or 4, whereby the moment about the shaft 46 due to the tension T of the strip is greatly increased, so that conversely a lower tension is produced by a given fluid pressure or spring force which biases the rolls against the strip. For example, referring to Fig. 4, it may be seen that the resultant force P exerted by the strip on each roll is approximately 21'". The moment MD exerted by the strip about the shaft 46 in the double roll application approximates 4T where 'y is the perpendicular distance of the force F from the shaft 46. Since the value of v may be approximately one half of the term R cos (0 in the high tension arrangement, this means that MDEIGIWS. The value would approximate 6Ms for the arrangement shown in Fig. 3. It may be made even higher than IOlVis for an arrangement similar to that of Fig. by so moving the rolls relative to each other as to decrease the included angle between the portions of the strip on each side of the rolls.

In order to provide for operating the strip H at widely separated values of tension, the mechanical construction of the tensiometer may take many different forms. One or" these may be such as shown in Figs. 5 and 6. It will be seen from these figures that the rolls t3 and 24 may be rotatably mounted on shafts 52 and 63, respectively, which may be supported by a. single support plate 55, or which may extend between spaced support plates i5 and 6 5, as shown. The support plates may be rotatably mounted by means such as the shaft 46, which supports the plate 45 and extends through a sleeve 5'! rotatably mounted in suitable bearings 63 and 69. The

plate 64 may be rctatably supported by means I of a rotatable shaft 55.

The support plate 35 may be operatively connected to the sleeve 5'! by means of latches H1 and TI which may be pivotally mounted adjacent the periphery of the support plate 35; for positioning in recesses T3 in the periphery of a flange The latch H may be provided with a handle 75, and may be operatively connected to the latch it by suitable means such as the lever mechanism it, so that both of the latches may be operated simultaneously. The positions of the shafts 62 and S3 and the latches 7i may be such that the operating angle 0 of the axis or axes of the roll or rolls, relative to the free path position of the strip, in this case the horizontal, is approximately 35 to 60 degrees.

The fluid pressure means 41 may be operatively connected to the rolls by being connected to the flange 14 in any suitable manner, such as by means-of a cleyis 18, for transmitting the strip tensioning force to the rolls 43 and 44 through the latches '10 and "H. When it is desired to thread the strip about the rolls, the handle 15 may be operated to release the latches Ill and H, so that the support plate 45 be rotated in a counterclockwise direction about 120 degrees. The strip [2 may then be passed directly between the rolls as shown in Fig. 2, and upon return of the support plate to the position shown in Fig. 3, the strip will be threaded over the roll 43 and beneath the roll 44. If desired, the strip may be fed between the rolls without first rotating the plate 45, so that upon subsequent rotation of the plate 45 the roll 44 will occupy the upper position.

For the purpose of facilitating threading of the strip, means such as the motor 80 may be utilized either in conjunction with or in place of the latch mechanism for providing relative rotation of the support plate 45 and flange E4. The motor 36 may, for example, be mounted on a bracket 82 secured to the sleeve 3'! and provided with a worm gear 83 for engaging a gear segment 84 mounted on the shaft 45. Normally the worm gear and segment provide a locking relation between the shaft 46 and the sleeve 67. The motor may be controlled in any suitable manner to rotate the shaft 45 relative to the sleeve for threading and then return it to the desired operating position to tension the strip.

When operating in the high tension range the strip [2 is merely passed over the upper roll 43 as shown in Fig. 1, and the tension control system operates in the usual manner to bias the roll 43 against the strip for maintaining the desired tension; When. however. it is desired to operate the tensiomcter in the low tension range, the plate may be rotated 120 to 180 degrees whereupon the strip l2 may be passed directly between the rolls 43 and 44 as shown in Fig. 2. The support plate 45 may then be rotated in a clockwise direction through 120 to 180 degrees so that the rolls 43 and 44 substantially change positions. In this position the strip i2 is doubly deflected from its free path so that the restoring force produced for a given tension in the strip is much greater than that exerted by the strip I? when it is disposed as shown in Fig. 1. For the arrangement shown in Fig. 4, the plate is rotated in a counterclockwise direction after passing the strip between its rolls. Accordingly, the tensioineter may be operated with the same pressure in the fluid pressure means 41, and with the regulator 38 adjusted the same as for the roll arrangement shown in Fig. l, and yet maintain a much lower tension in the strip by reason of the increased reaction effect of the strip tension.

Referring to Fig. 8, a different embodiment of the invention is shown wherein the shaft extension 42 which connects the tensiometer to the regulator 33, may be operatively connected to the shaft 43 of the tensiometer by mean of a differential device 86 having a pair of planetary gears mounted in a rotatable housing 81. The fluid pressure means 41 may be operatively connected to the support plate 45 of the rolls 43' and 44 by means such as the clevis 88 and pin 89, so as to be readily detachable therefrom.

When it is desired to thread a strip of material about the rolls 43 and 44, the fluid pressure means may be disconnected from the support plate 45 by removing the pin 89, and the shaft extension 42 may be locked in position by means of a suitable brake device 34. The support plate 45 now be rotated through about 120 to 180 degrees in a counterclockwise direction by operating the handle 92 of the housing 8?, whereupon the strip I2 may be passed directly between the rolls 43 and 44. The support plate 45 may then be returned to its original position by actuating the handle 92, whereupon the strip is doubly deflected and the fluid pressure means may be reconnected to the support plate 45 by replacing the pin 89 in the cl-evis 88. When the brake device 90 is released, the tensiometer is then ready for operation. When operation in the high tension range is desired, the strip i2 is merely passed over the upper roll 43 in the manner shown in Fig. 1 of the drawing.

In Fig. 9 a further modification of the invention is shown wherein the tensiometer rolls 43 and 44 may be rota-ta'bly supported by the shaft 45 by means of a support plate 93 provided with oppositely positioned knife-edge bearings 94 and $35 for engaging a knife edge $5 of the actuating means 91.

The actuating means 8? may, for example, comprise an upright shaft 9% having a collar 99 adjacent the upper end for engaging a spring H30 which biases the shaft upwardly. The lower end of the shaft may be provided with suitable damping means being, for example, provided with a piston I0! having bypass openings I02, and which may operate in a cylinder #33 containing a suitable fluid such as oil 104.

In order to eliminate the necessity for back and forth rotation of the support plate 93, provision may be made for rotating the support plate in a clockwise direction only, in order to facilitate positioning the strip without having to thread it around the rolls 43 and 44, when operating in the low tension range. The actuating means 3'! may, for example, be pivotally mounted between a pair of spaced upright arms I35 on a support member, and means such as the spring I46 utilized for normally biasing the upper end of the actuating means toward the support plate. The support plate 53 may be provided with a double cam surface E68 about the periphery for engaging a guide roller 1 it.

The cam surface may be so arranged that when the support plate 93 is rotated in a clockwise direction, the l znife edge separates from the knife-edge bearing 54 and the actuating means 91 is tilted so that the knife-edge bearing 93 clears the tension roll 44 and the opposite knife-edge bearing 95, and then drops into position for engaging the knife-edge bearing 95. Thus the strip i2 may be fed directly between the rolls 43 and 44 and the support plate 93 may be then rotated through degrees to produce a double deflection in the strip, whereupon the knife edge 93 will be positioned for engagement with the knife-edge bearing 35 for applying the tensioning force to the rolls for operation in the low tension range.

Referring to Figs. 10 and 11, the reference numeral H5 may denote, generally, a springoperated tensiometer of the double-roll type. In this modification of the invention the tension rolls 43 and 44 may be mounted on a support plate H6, which may be rotatably mounted on a shaft 46. When such a tensiometer is used for tensioning relatively narrow strip, the rolls need be supported at the one end only and they may be open at the other end. Accordingly, the strip may be readily threaded about the rolls for operation in thelow tension range from the open ends of therolls after it has been passed between both of the roll stands.

- The support plate H6 may be provided with a suitable bearing are adjacent the periphery for engaging a knife edge E2! on a movable rod or shaft 22, which may be biased upwardly by means of a spring 23 for biasing the rolls against the strip. The lower end of the shaft i222 may be connected to a piston I25 in a dashpot cylinder 12% mounted on a support E21 by means of knife-edge bearings I28 on opposite sides thereof. The tensiometer H may be operatively connected to regulating means such as described in connection with the system of Fig. l for regulating tension in a strip, or may be connected to indicating means llitl to indicate the tension in a strip of material. The connection to the indicating means may be eifected in any suitable manner, such as by means of synchrotie devices lEi and E32 through a gear segment I33 connected to the shaft 36. The tension indicating means 139 may be provided with a single dial 534 having a double scale for indicating tensions in both the high and low ranges, since the different methods of the threading the strip over the rolls change the force acting on the spring I23 by reason of the strip tension, and thus change the roll position. The indicating means follows changes in the roll position since the tension'is proportional to the roll position in spring actuated tensiometers.

From the above description and the accompanying drawings, it will be apparent that I have provided, in a simple and effective manner, for operating tensiometers at values of tension which differ widely from each other. According to the several embodiments of my invention, the tensiometers may be easily changed from the high to the low scale without requiring threading of the strip around the tension rolls in different directions. Since the same moving parts are used in both the high and low tension scales, the inertia characteristics of my double-range tensiometer the same for both ranges of tension, and the tonsiometer is rendered more accurate over a wider range of values. Operation of the tensiometer in the most suitable operating position .is effected for both high and low values of tensions.

Since certain changes may be made in the above-described construction and different embodiments of the invention may be made without departing from the spirit and scope thereof, it

isintended that all the matter contained in the above description and shown in the accompanying drawings shall be considered as illustrative and not in a limiting sense.

I claim as my invention:

1. In a tensiometer for producing diiferent values of tension in a strip between two work devices, a support plate rotatable about an axis transverse of and substantially parallel to the strip, means for applying a restoring torque to the support plate for maintaining it in a predetermined operating position, connecting means detachably connecting said means to the support to permit rotation of the support relativeto said torque applying means, and a pair of substantially parallel spaced apart rolls rotatably supported by the support at one end only for rotation about spaced apart axes substantially parallel to and on diametrically opposite sides of the axis of the support for engaging the strip either singly or together to provide a single or a double deflection in the strip for high and low values of tension.

2. A tensiometer comprising, support means mounted on a rotatable shaft, biasing means for applying a resilient restoring force to the shaft for maintaining it in a predetermined operating position, a pair of rolls rotatably supported by shafts projecting from said support means and having spaced axes parallel to and on diametrically opposite sides of the shaft, and latch means detachably connecting the support means and the biasing means whereby a strip of material may be threaded straight between the rolls and the support may be rotated relative to the biasing means so that the rolls positioned on opposite sides of the strip of material produce a double deflection therein from the straight path therebetween.

3. A tensiometer comprising, a rotatable support, a pair of rolls mounted on the support in fixed spacial relation to each other and on opposite sides of the axis of rotation of the support, a movable stop, latch means detachably connecting the support to the stop to permit rotation of the support relative to the stop, and means applying a resilient restoring force to the stop to deflect a strip of material from a normal path.

4. A double range tensiometer comprising, stop means rotatable about an axis transverse of and substantially parallel to a strip of material, means for applying a resilient operating torque to the stop means, a support rotatable about the axis of the stop means, a pair of rolls rotatably supported on the support means about axes parallel to and on opposite sides of the axis of the stop means, and latch means connecting the support and the stop means operable to transmit the operating torque to the support and also permit rotation of the support relative to the stop means.

5. A tensiometer comprising, a support rotatable about an axis transverse of and parallel to a strip of material, a pair of tensiometer rolls for engaging the strip to doubly deflect it rotatably supported on the support about relatively fixed spaced axes parallel to and displaced from the axis of rotation of the support, resilient torque means normally biased into operative connection with the support radially of the axis of rotation of the support, and means including a cam rotatable with the support for engaging guide means on the torque means to permit rotation of the support without interference from the torque means from a straight strip threading position to an operating position to doubly deflect the strip.

6. A double range tensiometer for tensioning a strip of material passing between two work devices comprising, a support plate rotatable about a substantially horizontal axis and having aprojection adjacent one edge, means cooperative with the projection for applying a resilient restoring force to the support plate including an upright shaft biased to a predetermined position by a spring and provided with a damper and a pair of rolls projecting from and rotatably supported by the plate for either singly or jointly engaging a strip of material to be tensioned, the

- axes of said rolls being on opposite sidesof the 9 lying between 35 and 60 degrees to the pass line of the strip.

7. In a double-roll tensiometer, a rotatable sleeve having a flange at one end, means connected to the flange for applying a resilient restoring torque for retaining the sleeve in an operating position, a support rotatably mounted on a shaft extending through the sleeve, driving means operatively connecting the sleeve and shaft for transmitting torque between the rotatable sleeve and the support and also rotating the support relative to the sleeve, and a pair of tension rolls for engaging opposite sides of a strip to be tensioned positioned on the support on opposite sides of the shaft.

8. In a tensiometer, a support plate rotatably mounted on a shaft, a pair of spaced apart tension rolls positioned on the support for engaging and deflecting a strip to be tensioned in the operating position, means detachably connected to the support for applying a resilient tensioning force to the support, a shaft extension for connection to a regulator, means for braking said shaft extension, and means including a differential connecting the shaft and shaft extension for rotating the support for threading a strip between the rolls and returning it to the operating position.

9. The combination in a double-range tensiometer of upper and lower tension rolls disposed in fixed spaced relation to engage the lower and upper sides respectively of a strip to produce a double deflection therein, the axes of said rolls I lying in a plane inclined between to degrees to the free path of the strip, support means rotatable about an axis parallel to and transverse of the strip intermediate the longitudinal axes of the rolls for positioning the rolls, biasing means, and means detachably connecting the biasing 10 means to the support for applying a resilient restoring torque to the support means.

10. In a double-roll tensiometer, a pair of spaced tension rolls, means for producing a resilient biasing force comprising an upright movable shaft having a dashpot damper.

11. A tensiometer device comprising, a rotatable support having a definite axis of rotation, a pair of rolls rotatably mounted on the support in parallel fixed spaced relation to each other and on opposite sides of the axisof rotation of the support, a rotatable membefcoaxial with the support, biasing means operatively connected to the rotatable member, and connecting means selectively operable to one position to lock the support and rotatable member in fixed rotational relation relative to each other for biasing the support to a position in which the rolls doubly defiect a strip of material from a normal path between the rolls, and to another position to permit rotation of the support relativeto the rotatable member.

GERHARD P. LESSMANN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,918,968 Keeney et al. July 18, 1933 2,185,836 Croco Jan. 2, 1940 2,215,329 Lessmann Sept. 17, 1940 2,223,718 Cook Dec. 3, 1940 2,249,839 Lessmann July 22, 1941 FOREIGN PATENTS Number Country Date 144,916 Switzerland Apr. 16, 1931 

